In UMTS (Universal Mobile Telecommunications System) networks, for the purpose of improving spectral efficiency and further improving data rates, by adopting HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access), it is performed exploiting maximum features of the system based on W-CDMA (Wideband Code Division Multiple Access). For the UMTS network, for the purpose of further increasing high-speed data rates, providing low delay and the like, Long Term Evolution (LTE) has been studied (Non-patent Document 1).
In the 3G system, a fixed band of 5 MHz is substantially used, and it is possible to achieve transmission rates of approximately maximum 2 Mbps in downlink. Meanwhile, in the LTE system, using variable bands ranging from 1.4 MHz to 20 MHz, it is possible to achieve transmission rates of maximum 300 Mbps in downlink and about 75 Mbps in uplink. Further, in the UMTS network, for the purpose of further increasing the wide-band and high speed, successor systems to LTE have been studied (for example, may be called LTE Advanced or LTE Enhancement, (hereinafter, referred to as “LTE-A”)).
In downlink of the LTE system (for example, Rel.8) is defined a CRS (Cell-specific Reference Signal) tied to a cell ID. The CRS is used in measurement of downlink channel quality (CQI: Channel Quality Indicator) for scheduling and adaptive control and the like, as well as being used in demodulation of user data. Meanwhile, in successor systems (for example, Rel.10) to LTE, a CSI-RS (Channel State Information-Reference Signal) is studied to be dedicated to CSI (Channel State Information) measurement.